1. Field
The present disclosure relates to interlayer video encoding and decoding methods, and more particularly, to a method of adaptively compensating for a luminance difference between interlayer images.
2. Description of the Related Art
As hardware for reproducing and storing high resolution or high quality video content is being developed and supplied, a need for a video codec for effectively encoding or decoding the high resolution or high quality video content is increasing. According to a conventional video codec, a video is encoded according to a limited encoding method based on a coding unit having a predetermined size.
Image data of the space domain is transformed into coefficients of the frequency domain via frequency transformation. According to a video codec, an image is split into blocks having a predetermined size, discrete cosine transformation (DCT) is performed on each block, and frequency coefficients are encoded in block units, for rapid calculation of frequency transformation. Compared with image data of the space domain, coefficients of the frequency domain are easily compressed. In particular, since an image pixel value of the space domain is expressed according to a prediction error via inter prediction or intra prediction of a video codec, when frequency transformation is performed on the prediction error, a large amount of data may be transformed to 0. According to a video codec, an amount of data may be reduced by replacing data that is consecutively and repeatedly generated with small-sized data.
A multi-layer video codec encodes and decodes a first layer video and one or more second layer videos. The multi-layer video codec may remove temporal and spatial redundancies of the first layer video and the second layer videos and redundancy between layers, thereby compressing data of the first layer video and the second layer videos.
However, according to positions of cameras, illumination may differ. Then, each camera may not be calibrated to have the same physical characteristic, and thus, image signals may be slightly different from each other. Therefore, a correlation between respectively layer videos may be lowered, and when encoding is performed by referring to images acquired from layers that are at different views, it may be difficult to acquire accurate disparity vectors. Also, as a direct current (DC) component of a residual signal increases, compression efficiency may degrade.